Introduction to Ornithopoda

The Ornithopoda are a group of medium to large plant-eating
dinosaurs. They include one of the earliest discovered
dinosaurs, Iguanodon, as well as the famous crested and "duck-billed" hadrosaurs. Several
of these are noted for the spacious and bizarrely shaped sinus regions in their
skulls. All ornithopods were herbivores and mostly bipedal.

Ornithopods are one of three major groups of Ornithischia, or
"bird-hipped" dinosaurs. They are closely related to the Marginocephalia.